1. Field of the Invention
The present invention relates to an improved method for manufacturing a composite sintered structure. More particularly, it relates to a method for manufacturing a composite sintered structure comprising a plurality of conductive and insulative layers and for use in, for example, an integrated semiconductor circuit device.
2. Description of the Prior Art
Multilayer structures manufactured by stacking several ceramic sheets each of which has conductive patterns thereon and sintering the stack to form a unitary structure are generally known. As described by Stetson, U.S. Pat. No. 3,189,978, conductive layers of desired patterns are printed on the surfaces of green ceramic sheets formed separately, respectively. Holes are formed in desired interconnection portions of the respective substrates and the respective holes are filled with conductor material. The resultant sheets are stacked into a laminated body so that the conductive layers may have desired interconnections.
Then, the stack is sintered to obtain a multilayer structure, such as multilayer interconnection substrate or a multilayer interconnection package.
With such prior art technique, there are various disadvantages such that the holes for interconnections are sometimes not fully filled with conductive material, resulting in disconnection among conductive layers formed on the different sheets, such that since relatively thick ceramic sheets are used, the number of conductive layers to be stacked is limited.
In order to eliminate such disadvantages of the stacked ceramic sheet technique, it is proposed by Hargis, U.S. Pat. No. 3,549,784, to screen-print insulative and conductive material alternatively on a ceramic body. According to the art, since very thin insulative and conductive layers are printed, the thickness of the completed ceramic structure is extremely reduced and therefore the number of the conductive layers are increased. Also, the conductive layers printed on the different insulative layer planes are connected with the printed conductive layers without discontinuity.
In the screen printing technique, however, there occurs a problem of deformation of the final ceramic structure because of differences of the shrinkage rates among ceramic base, ceramic and metallic pastes. In order to avoid such deformation, it is proposed by Hargis, U.S. Pat. No. 3,549,784 that to provide on the reverse of the ceramic base a metallic layer which has an area and thickness similar to the metallic layer or layers printed on the reverse of the ceramic base. This resolution requires, however, additional printing steps, resulting in increase of manufacturing cost, and increase of the thickness of the final ceramic structure.